/*
 * Metadata - jQuery plugin for parsing metadata from elements
 * 
 * Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
 * 
 * Dual licensed under the MIT and GPL licenses:
 * http://www.opensource.org/licenses/mit-license.php
 * http://www.gnu.org/licenses/gpl.html
 * 
 * Revision: $Id: jquery.metadata.js 4187 2007-12-16 17:15:27Z joern.zaefferer $
 * 
 */

/**
 * Sets the type of metadata to use. Metadata is encoded in JSON, and each
 * property in the JSON will become a property of the element itself.
 * 
 * There are three supported types of metadata storage:
 * 
 * attr: Inside an attribute. The name parameter indicates *which* attribute.
 * 
 * class: Inside the class attribute, wrapped in curly braces: { }
 * 
 * elem: Inside a child element (e.g. a script tag). The name parameter
 * indicates *which* element.
 * 
 * The metadata for an element is loaded the first time the element is accessed
 * via jQuery.
 * 
 * As a result, you can define the metadata type, use $(expr) to load the
 * metadata into the elements matched by expr, then redefine the metadata type
 * and run another $(expr) for other elements.
 * 
 * @name $.metadata.setType
 * 
 * @example
 * <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">
 * This is a p
 * </p>
 * @before $.metadata.setType("class")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label ==
 *        "Label"
 * @desc Reads metadata from the class attribute
 * 
 * @example
 * <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">
 * This is a p
 * </p>
 * @before $.metadata.setType("attr", "data")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label ==
 *        "Label"
 * @desc Reads metadata from a "data" attribute
 * 
 * @example
 * <p id="one" class="some_class">
 * <script>{item_id: 1, item_label: 'Label'}</script>This is a p
 * </p>
 * @before $.metadata.setType("elem", "script")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label ==
 *        "Label"
 * @desc Reads metadata from a nested script element
 * 
 * @param String
 *            type The encoding type
 * @param String
 *            name The name of the attribute to be used to get metadata
 *            (optional)
 * @cat Plugins/Metadata
 * @descr Sets the type of encoding to be used when loading metadata for the
 *        first time
 * @type undefined
 * @see metadata()
 */

(function($) {

	$.extend({
				metadata : {
					defaults : {
						type : 'class',
						name : 'metadata',
						cre : /({.*})/,
						single : 'metadata'
					},
					setType : function(type, name) {
						this.defaults.type = type;
						this.defaults.name = name;
					},
					get : function(elem, opts) {
						var settings = $.extend({}, this.defaults, opts);
						// check for empty string in single property
						if (!settings.single.length)
							settings.single = 'metadata';

						var data = $.data(elem, settings.single);
						// returned cached data if it already exists
						if (data)
							return data;

						data = "{}";

						if (settings.type == "class") {
							var m = settings.cre.exec(elem.className);
							if (m)
								data = m[1];
						} else if (settings.type == "elem") {
							if (!elem.getElementsByTagName)
								return undefined;
							var e = elem.getElementsByTagName(settings.name);
							if (e.length)
								data = $.trim(e[0].innerHTML);
						} else if (elem.getAttribute != undefined) {
							var attr = elem.getAttribute(settings.name);
							if (attr)
								data = attr;
						}

						if (data.indexOf('{') < 0)
							data = "{" + data + "}";

						data = eval("(" + data + ")");

						$.data(elem, settings.single, data);
						return data;
					}
				}
			});

	/**
	 * Returns the metadata object for the first member of the jQuery object.
	 * 
	 * @name metadata
	 * @descr Returns element's metadata object
	 * @param Object
	 *            opts An object contianing settings to override the defaults
	 * @type jQuery
	 * @cat Plugins/Metadata
	 */
	$.fn.metadata = function(opts) {
		return $.metadata.get(this[0], opts);
	};

})(jQuery);